DESCRIPTION:(Adapted From The Applicant's Abstract.) A great deal is known about the hearing of mature humans, but relatively little about how early experience affects these important abilities. In particular little is known about how we come to perceive patterns in complex sounds, an essential part of normal attention and communication. This research quantifies the roles of early conductive hearing loss on hearing development. The studies take advantage of a unique population of human patients in a combination of careful psychoacoustical or sensory experiments, and more integrative or cognitive experiments, to discover how we learn to appreciate relevant patterns in complex sounds. Patients born with a maximum conductive hearing loss will be used which is surgically corrected at different ages and binaural processing in the "new" ear of these cooperative subjects will be used. The hypothesis to be evaluated is that different aspects of hearing (termed detections, distractions, discriminations, bisensory integration,and attributes) emerge independently. It appears that the early "deprivation" leads to an interesting deficit in the perception of simple patterns. The data will provide new and cohesive observations on how our perceptions become structured and organized. The results will have far-reaching implications for the understanding and treatment of hearing and communication disorders and for general theories of perceptual disorders.